for the love of basic pharmacognosy

1. EVALUATION OF CRUDE DRUGS
DR IK AMPONSAH

2. CRUDE DRUG?
• A crude drug is any naturally occurring, unrefined
substance derived from organic or inorganic
sources such as plant, animal, bacteria, organs or
whole organisms intended for use in the
diagnosis, cure, mitigation, treatment, or
prevention of disease in man or other animals.
• Give examples:

3. Why evaluation of crude drugs?
Biochemical variation in crude drugs
Deterioration due to treatment and/or storage
Substitution and adulteration
1. Carelessness
2. Ignorance
3. Fraud
Crude drug evaluation ensures it identification
and determination of quality and purity

4. IDENTIFICATION?
• Key to quality of crude drugs
• Usually done by
1. A qualified, experienced or specialised
personnel (eg. )
2. Comparison with authentic of standard
herbarium specimen.

5. QUALITY?
• The intrinsic value of the drug i.e nature and
amount of active or medicinal principle
• Examples of active principles……………………….
HOW DO YOU MAINTAIN QUALITY?
1. Select proper source of crude drug i.e
2. Collect at appropriate time
3. Collect the required parts
4. Proper preparation i.e cleaning and drying to
prevent contamination

6. PURITY
• Can be achieved by
proper identification and
quality assurance

7. METHODS OF EVALUATION OF CRUDE
DRUGS
• Basically five methods are used. Can be
qualitative or quantitative
1. Organoleptic evaluation
2. Microscopical evaluation
3. Physical evaluation
4. Chemical evaluation
5. Biological evaluation

9. • Definition: evaluation of crude drugs using the
sense organs
• DIVIDED INTO TWO
• Morphological evaluation and
• Sensory evaluation

10. Morphological evaluation
• Shape & size for entire drugs not powders
• Leaves
• Flowers
• Barks
• Fruits
• Seeds

11. SENSORY EVALUATION
• Based on measuring colour, taste, odour, texture
etc
• Colour-external and internal
• Odour: May be odourless or have a distinct odour.
Terms for describing odour includes aromatic,
spicy, fruity, pungent etc
• Texture: touch either smooth or rough
• Taste: May have a distinct taste or tasteless.
Terms for describing taste includes acid, sweet,
alkaline, bitter, saline, tasteless etc

12. Distinctive sensations to the tongue
a- mucilaginous and oily (soft feeling) e.g.,
linseed.
b- astringent (contraction of the tissues of the
mouth) indicates presence of tannin.
c- pungent (warm biting sensation) e.g., ginger.
d- acrid (irritant sensation) e.g., coca.
e- nauseous (those tending to excite vomiting),
Ipeca.

13. CLASS ACTIVITY
• Describe the shape of 5 medicinal leaves
• The inner and outer colour of some barks
• The odour of some crude drugs

14. PHYSICAL EVALUATION
• The physical evaluation of crude drugs is done by the
determination of various physical
characteristics/parameters using physico-chemical
techniques.
• Physical parameters determined includes
1. Optical rotation
2. Specific gravity
3. Solubility
4. Refractive index
5. Melting point
6. Moisture content
7. Foreign organic matter
8. Ash value
9. Extractive values

17. MOISTURE CONTENT
• The moisture content of a crude drug is
responsible for it decomposition due to microbial
attack or chemical changes
• Excess moisture in a crude drug, at relatively high
temperatures, will lead to activation of enzymes
and given suitable conditions to the proliferation
of microorganisms.
• Presence of moisture in crude drugs is
uneconomical

18. MOISTURE CONTENT
• The WHO states that the moisture content of a
crude drug should not exceed 10%w/w
• A large number of methods are now available for
moisture content determination.
1. Loss on drying method
Material heated between 100-105C until a constant
weight is obtained. Not suitable for materials
containing volatile oils
2. Weighed drug in a dessicator over phosphorus
pentaoxide

19. Moisture content
• Dean stark apparatus-distillation method.
Material is boiled in a flask with an inert solvent
(toluene or xylene). Moisture separated and
measured.
• Gas chromatography method
• Karl Fischer method-chemical method
Involves titrimetry (disadvantage is the instability of
the reagent)
• Spectroscopic method
• Electrometric method (conductimetric method)